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A nursery experiment was conducted to look into the function of arbuscular mycorrhizal Fungi ( AMF ) on Cd ( Cd ) and P ( P ) consumption by Sedum alfredii Hance ( a Cd hyperaccumulator ) , and Ipomoea aquatica Forks from Cd-contaminated vegetable dirts. In this experiment, four interventions were conducted: ( 1 ) I. aquatica ( monoculture ) ; ( 2 ) S. alfredii with I. aquatica ( interculture ) ; ( 3 ) interculture with GC Fungis ( GC: Glomus caledonium 90036 ) ; and ( 4 ) interculture with GV Fungis ( GV: Glomus versiforme HUN02B ) . The effects of AMF on colonisation rate, works biomass, Cd and P contents of twenty-four hours 56 S. Alfredii, the effects of S. alfredii and AMF on dirt pH, dirt EC, dirt available Cd and P contents, dirt entire Cd content and dirt acerb phosphatase activity, the effects of S. alfredii and AMF on fresh biomass, Cd and P content of I. aquatica were examined. Comparing to command, it was found that AMF increased the colonisation rate, works biomass, Cd and P consumption of twenty-four hours 56 S. Alfredii, while S. alfredii and AMF reduced dirt available Cd and P contents and increased dirt acid phosphatase activity. S. alfredii did non impact the growing and production of I. aquatica. Furthermore, with AMF vaccination, I. aquatica P consumption was increased and Cd consumption was reduced. All these consequences indicated that vaccination of AMF and S. alfredii, there was a important decrease ( P & lt ; 0.05 ) in Cd content in comestible veggies ( I. aquatica ) , which in bend would better the nutrient safety.

Cadmium ( Cd ) is a normally known extremely toxic metal. Among the top 20 toxins, Cd has been ranked figure 7. It is chiefly due to its negative influence on the enzymatic systems of cells ( Al-Khedhairy et al. , 2001 ; Sanita et al. , 1999 ) . Nowadays, in different states, big countries of land have been contaminated by Cd and other heavy metals, due to the application of sludge or urban composts, fertilisers, pesticides, emanations from waste incinerators, waste H2O irrigation, residues from metalliferous excavation, and the metal smelting industry ( McGrath et al. , 2001 ; Reeves and Baker, 2000 ; Yang et al. , 2002 ) . Furthermore, Cd is easy transferred to human nutrient concatenation. It is no uncertainty that Cd taint is a great menace to human wellness. Hence, these cause modification of marketing agricultural merchandises and cut downing the profitableness of the agricultural industry. Furthermore, Cd can remain in dirt over 1000s old ages ( Alloway, 1995 ) .

1.2 Cd-contaminated dirts in China

Nowadays, because of the economic in China develops quickly, heavy metal taint of agricultural dirts has besides become progressively serious in China ( Li et al. , 1997a, B ; Chen et al. , 1999 ) . Furthermore, agribusiness in China has become progressively rely on agrochemical use. ( Li et al. , 1997a, B ) When uninterrupted application of agrochemicals, it will potentially worsen the accretion of heavy metals in agricultural dirts over clip ( Siamwalla, 1996 ; Chen et al. , 1999 ) . Therefore, Cd-contaminated dirts are serious job in China.

1.3 Cd hyperaccumulator – S. alfredii.

In order to cover with the Cd-contaminated dirt, phytoremediation is a normally used technique. By utilizing green workss, which offers the benefits of low cost, and environmentally sustainable, to clean up contaminated dirts ( Salt et al. , 1998 ; Long et al. , 2002 ) . Yang, et Al. ( 2004 ) proved that Sedum alfredii is a new powerful Cd hyperaccumulator, so it is a utile works stuff for phytoremediation of Cd-contaminated dirts and do decrease of dirt available Cd. In add-on, it has features of fast growing, big biomass, nonsexual reproduction, and perennial. Furthermore, harmonizing to Yang et Al. ( 2001 ) , S. alfredii can turn up to 40 centimeters height and propagate 3-4 times in a twelvemonth if the environmental conditions are favourable. Therefore, in my survey, intercropping of S. alfredii and I. aquatica is choosen. S. alfredii were planted in order to cut down dirt available Cadmium and in bend cut down the Cd consumption by I. aquatica.

1.4 Function of Arbuscular mycorrhizal fungal ( AMF ) .

Arbuscular mycorrhizal fungal ( AMF ) symbioses are mutualistic interactions between Fungis and most workss. So, workss obtain foods, peculiarly P, through mutualism ( Smith et al. , 2003 ) . AMF associations with works roots, through the hyphae which explore the dirt off from the root surface, so it increases the effectual absorbing zone of the root ( Wang et al. , 2007 ) . Nevertheless, some surveies proved that AMF isolated from contaminated dirts are able to digest higher metal concentrations ( Gonzalez-Chavez et al. , 2002 ; Vivas et al. , 2005 ) . Therefore, in my survey, AMF were inoculated to heighten the phytoremediation power of S. alfredii.

1.5 Intercropping of S. alfredii and I. aquatica.

Ipomoea aquatica is a popular and common leafy vegetable in China. However, past research showed that I. aquatica can be easy contaminated by Cd in the dirt ( Wang, J. L et Al. 2007 ) . Therefore, in my survey, S. alfredii Hance was used to phytoremediate the Cd-contaminated dirt by uptaking more Cadmium from dirt and cut downing dirt Cd content, in bend cut down Cd consumption by I. aquatica.

1.6 Experimental aims

The aims of this experiment were to look into the effects of AMF on colonisation rate, works biomass, Cd and P content of Sedum alfredii. And, analyze the effects of S. alfredii and AMF on dirt pH, EC, entire Cd content, bioavailable Cd content and P content and acerb phosphatase activity of dirt. Furthermore, to look into the effects of Sedum alfredii and AMF on fresh biomass, Cd and P consumption of Ipomoea aquatica. The purpose of my survey was to heighten Cd uptake by S. alfredii and so cut down Cd content in I. aquatica. Therefore, cut down the hazard of dirt contaminations come ining the human nutrient concatenation.

Materials and Method

2.1 AM Fungal inoculant

Two AMF inoculant were used in this experiment. One contained merely a AMF strain, A Glomus caledonium 90036 ( GC ) , which was isolated from a fluvo-aquic dirt in Hennan Province, China, and was deposited at the Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China. The other besides contained merely one AMF strain, Glomus versiforme HUN02B ( GV ) , which was isolated from a grass dirt in Hunnan Province, China, A and was deposited at the Institute of Plant Nutrition and Resources, Beijing Academy of Agriculture and Forestry. As a mixture of rhizospheric dirt incorporating spores, hyphae, and mycorrhizal root fragments, the AM inoculant were propagated on sudangrass [ Sorghum Sudanese ( Piper ) Stapf. ] grown in an autoclaved ( 121A°C for 1 H on three consecutive yearss ) sandy dirt in pots for two consecutive extension rhythms ( two month each ) . At the same clip, the non-mycorrhizal inoculant was besides prepared with the same sterilized substrate on which sudangrass was cultivated under the same conditions. All inoculant were air-dried and sieved ( 2 millimeter ) before vaccination.

aˆˆ2.2 Soil Preparation

The dirts were collected from Guangzhou Viaoying small town, which is a vegetable field. The dominant harvest species planted on these site were tomato, beans, etc. As those harvested veggie will be sell to Hong Kong, so we choose this field dirt as our experiment samples. In this site, the dirts were suspected being polluted. The possible pollution beginnings were river deposit, fertiliser, pesticides, etc. In the field country, 4 to 6 points were indiscriminately choosen to roll up the dirt samples. Dirt samples were collected 0-15 centimeter in deepness, air-dried and sieved to & lt ; 2mm.

2.3 Experimental design

In this pot experiment, four interventions were conducted: ( 1 ) I. aquatica ( monoculture ) ; ( 2 ) S. alfredii with I. aquatica ( interculture ) ; ( 3 ) interculture with GC Fungis ( GC: Glomus caledonium 90036 ) ; and ( 4 ) interculture with GV Fungis ( GV: Glomus versiforme HUN02B ) . The Seeds of I. aquatica were brought from Hong Kong, the seeds were one hundred five. Hantong. Pot were arranged in a randomised complete block design with five replicates per intervention.

The pot used were 24cm ( radius ) x 22cm ( tallness ) . 2.4 kilogram of dirt are based. Then, base dirt were watered until H2O keeping capacity reach 75 % . On the top of the base soils, 150g of AMF were added. Seeds of I. aquatica were surface-sterilized with 0.5 % NaCLO and later washed several times with distilled H2O and germinated at 28 a„? ( 12h ) before seeding. 9 seeds were transplanted into each pot ( Fig. 1 ) and after outgrowth 6 seedlings were left. Afterward, add-on of 600g top dirts without irrigating. After outgrowth, dirt were watered until H2O keeping capacity reach 50 % . Plants were watered to keep dirt wet at approximately 50 % of H2O keeping capacity by adding tap H2O suring the ecperimental period.

S. alfredii were harvested after 56 yearss of growing. Mycorrhizal colonisation rate, dry biomass, Cd content and P content of twenty-four hours 56 S. alfredii were determined. After 28 yearss, wholly 3 samples of I. aquatica were harvested in each pot. After 56 yearss, all the remaning works samples were harvested. Fresh biomass, Cd content and P content of shoots and roots of twenty-four hours 28 and 56 I. aquatica were determined. Furthermore, after 56 yearss, all dirts are collected in order to find dirt pH, EC, entire Cd content, bioavailable Cd content and P content and acerb phosphatase activity.

Fig. 1. Figure shows the location of plantation and sowing in pot.

2.4 Mycorrhizal colonisation rate

Root of twenty-four hours 56 S. alfredii were cleaned in 10 % KOH, stained with 0.05 % trypan blue ( Philips and Hayman 1970 ) . The clean roots were cut into sections of about 1 centimeters in length. A indiscriminately selected fresh 100 segements of root samples were taken for the appraisal of root colonisation. The per centum colonisation was so determined by the grid intersect method ( Giovannetti and Mosse 1980 ) .

2.5 Chemical analyses

Dirt samples were air-dried, land, sieved through a 2mm screen, and so used to analyse the diethtylenetetraminepentaacetic acid ( DTPA ) extractible heavy metal concentrations ( Lindsay and Norvell, 1978 ) , pH and EC ( electro-conductivity ) and entire Cd. The values of dirt pH and electrical conduction ( EC ) A ( dirt: deionized H2O = 1:5 ) were measured by a pH metre ( Beckman ) and an EC metre ( Orion 160 ) , severally. Dirt samples were air-dried, land, sieved through a 0.15mm screen were used to analyse entire Cd. Soil sub-samples weighed 0.5g after oven drying at 105a„? for 12h. The dirt sub-samples ( 0.5g ) were mirowave digested by “ CEM Corporation ” Model Mars Xpress Microwave Digestion Systerm with concentrated HCL: HNO3: HClO4 at 6:2:4 volume ratio. The entire Cd concentration were so determined by Atomic Absorption Spectrometer ( Spectr AA-20 Varian ) . A standard mention stuff: NIST SRM 2711a Montana Soil II was used to verify the truth of Cd determined in dirts and the recovery rate was 94 % . Soil available P was tested by the Bray and Kurtz ( 1945 ) method, which employs an acid pull outing solution ( 0.025 M hydrochloric acid and 0.03 M ammonium fluoride ) , and the P concentration in the infusions was so determined utilizing a UV-Vis spectrophotometer ( UV-1061, Shimadzu, Kyoto ) based on the Mo bluish reaction ( Lu, 2000 ) . Dirt samples were air-dried for the check of dirt acerb phosphatase activity. It was determined by incubation at 37 A°C with acetate buffer ( pH 5 ) harmonizing to the method of Tabatabai ( 1982 ) , and is given in units of mg p-nitrophenol produced g-1 dirt 24 h-1.

Shoots and roots of I. aquatica samples were rinsed with tap H2O, so with deionized H2O, and weighed after oven drying at 70a„? for 48h. Then, workss samples were land with a chromium steel steel bomber and passed through a 0.15mm screen. For dried twenty-four hours 28 shoots and roots of I. aquatica, sub-samples were weighed 0.75g and 0.1 g severally. For dried twenty-four hours 56 shoots and roots of I. aquatica, sub-samples were weighed 1g and 0.5g severally. For dried twenty-four hours 56 shoots of S. alfredii, sub-samples were weighed 0.2g. They were digested by concentrated 8ml HNO3, were used to analyse entire Cd and P content. The concentration of Cd was determined by Atomic Absorption Spectrometer ( Spectr AA-20 Varian ) . A standard mention stuff: NIST SRM 1573a Tomato Leave was used to verify the truth of Cd determined in dirts and the recovery rate was 96 % . Concentrations of P were determined utilizing Mo bluish method ( Page et al. , 1982 ) .

2.6 Statistical Analysis

The informations were subjected to one-way analysis of discrepancy ( ANOVA ) utilizing the SPSS package plan ( SPSS Inc. , Chicago, Version 10.0 for Windows ) ( Wang, Zheng, and Chao, 2003 ) . Means and standard divergence were calculated for 5 replicate values. Means were compared by the Duncan ‘s multiple scope trial ( P & lt ; 0.05 ) .

Consequences

3.1 Colonization rate, works biomass, Cd content and P content of twenty-four hours 56 S. alfredii.

Although all S. alfredii were colonized ( Table 1 ) , there were important difference ( p & lt ; 0.05 ) between interventions. With vaccination of AMF, there was important addition ( p & lt ; 0.05 ) of mycorrhizal colonisation in of twenty-four hours 56 S. alfredii. Furthremore, with vaccination of GC Fungi, there was important addition ( p & lt ; 0.05 ) of twenty-four hours 56 S. alfredii dry biomass ( Fig. 2 ) . This indicated that with AMF colonisation, the growing of S. alfredii is enhanced. On the other manus, with vaccination of AMF, there was important addition ( p & lt ; 0.05 ) of Cd content in twenty-four hours 56 S. alfredii ( Fig 3A ) . This consequence indicated that S. alfredii has an extraordinary ability to absorb Cd and concentrate it in the aboveground tissue. However, there were no important difference of P content among three interventions ( Fig. 3B ) . Comparing two different AMF species, S. alfredii inoculated with GC Fungis had significantly higher ( p & lt ; 0.05 ) dry biomass and Cd content.

Table 1. Effectss of AMF on colonisation rate of twenty-four hours 56 S. alfredii in response to different intervention.

aˆˆ

Average Mycorrhizal colonisation ( % )

Inter

18.0 ( 3.81 ) B

Inter + GC

42.4 ( 7.09 ) a

Inter + GV

35.4 ( 7.60 ) a

Inter: interculture of Sedum alfredii and Ipomoea aquatica ; Inter+GC: interculture of Sedum alfredii and Ipomoea aquatica with vaccination of GC Fungi ; Inter+GV: interculture of Sedum alfredii and Ipomoea aquatica with vaccination of GV Fungi. Average values are presented with standard divergence in parentheses. Different letters in the same column show important difference by Duncan ‘s multiple scope trial at P & lt ; 0.05.

Fig. 2- Individual prohibitionist biomass ( g ) of twenty-four hours 56 Sedum alfredii with different interventions. All the informations are agencies of 5 reproductions, and the bars represent standard divergence. In different intervention, means with different letters are significantly different ( p & lt ; 0.05 ) . ( Inter: interculture of Sedum alfredii and Ipomoea aquatica ; Inter+GC: interculture of Sedum alfredii and Ipomoea aquatica with vaccination of GC Fungi ; Inter+GV: interculture of Sedum alfredii and Ipomoea aquatica with vaccination of GV fungi. )

( B )

Fig. 3- ( A ) Plant Cd content ( mg kg-1 dry biomass ) and ( B ) P content ( g kg-1 dry biomass ) of twenty-four hours 56 Sedum alfredii with different interventions. All the informations are agencies of 5 reproductions, and the bars represent standard divergence. In different intervention, means with different letters are significantly different ( p & lt ; 0.05 ) . ( Inter: interculture of Sedum alfredii and Ipomoea aquatica ; Inter+GC: interculture of Sedum alfredii and Ipomoea aquatica with vaccination of GC Fungi ; Inter+GV: interculture of Sedum alfredii and Ipomoea aquatica with vaccination of GV fungi. )

3.2 Day 56 dirt pH, EC, entire Cd content, bioavailable Cd content and P content and acerb phosphatase activity.

In different interventions, all dirt pH & lt ; 5.5, that means they are acidic ( Fig. 4A ) . However, with intercropping, there was important addition ( p & lt ; 0.05 ) of dirt pH. Furthermore, with vaccination of AMF, there were important addition ( p & lt ; 0.05 ) of dirt pH. Furthermore, with vaccination of GC Fungi, it showed a higher ability to do obvious addition ( p & lt ; 0.05 ) of dirt pH. On the other manus, there were no obvious difference of EC among interventions ( Fig. 4B ) .

Although there were no important difference of dirt entire Cd content among interventions ( Fig 5A ) , there were important lessening ( p & lt ; 0.05 ) of dirt available Cd content ( Fig. 5B ) in interculture with AMF vaccination. This indicates that intercropping with AMF vaccination, less Cd is available in dirt, that means workss could uptake less Cadmium from dirts.

Intercorpping caused decrease of dirt bioavailable P and important lessening ( p & lt ; 0.05 ) of dirt acerb phosphatase activity ( Fig. 6 ) . Furthermore, with vaccination of AMF, there were important lessening ( p & lt ; 0.05 ) of dirt bioavailable P and important addition ( p & lt ; 0.05 ) of dirt acerb phosphatase activity ( Fig. 6 ) .

( B )

Fig. 4- ( A ) Soil pH and ( B ) EC ( AµS cm-1 ) of twenty-four hours 56 dirts with different interventions. All the informations are agencies of 5 reproductions, and the bars represent standard divergence. In different intervention, means with different letters are significantly different ( p & lt ; 0.05 ) . ( Mono: monoculture of Ipomoea aquatica ; Inter: interculture of Sedum alfredii and Ipomoea aquatica ; Inter+GC: interculture of Sedum alfredii and Ipomoea aquatica with vaccination of GC Fungi ; Inter+GV: interculture of Sedum alfredii and Ipomoea aquatica with vaccination of GV fungi. )

( B )

Fig. 5- ( A ) Total Cd content ( mg kg-1 ) and ( B ) Soil bioavailable Cd ( mg kg-1 ) of twenty-four hours 56 dirts with different interventions. All the informations are agencies of 5 reproductions, and the bars represent standard divergence. In different intervention, means with different letters are significantly different ( p & lt ; 0.05 ( Mono: monoculture of Ipomoea aquatica ; Inter: interculture of Sedum alfredii and Ipomoea aquatica ; Inter+GC: interculture of Sedum alfredii and Ipomoea aquatica with vaccination of GC Fungi ; Inter+GV: interculture of Sedum alfredii and Ipomoea aquatica with vaccination of GV fungi. )

( B )

Fig. 6- ( A ) Soil available P ( mg kg-1 ) and ( B ) Soil acerb phosphatase activity ( mg g-1 24h-1 ) of twenty-four hours 56 dirts with different interventions. All the informations are agencies of 5 reproductions, and the bars represent standard divergence. In different intervention, means with different letters are significantly different ( p & lt ; 0.05 ) . ( Mono: monoculture of Ipomoea aquatica ; Inter: interculture of Sedum alfredii and Ipomoea aquatica ; Inter+GC: interculture of Sedum alfredii and Ipomoea aquatica with vaccination of GC Fungi ; Inter+GV: interculture of Sedum alfredii and Ipomoea aquatica with vaccination of GV fungi. )

3.3 Fresh biomass, Cd and P content of twenty-four hours 28 and 56 I. aquatica.

Comparing differment interventions of twenty-four hours 28 and 56 I. aquatica, twenty-four hours 56 I. aquatica had a higher fresh biomass, which are 3 times greater than that of twenty-four hours 28 I. aquatica ( Fig. 7 ) . There were no obvious difference of both twenty-four hours 28 and 56 I. aquatica shoot and root frsh biomass, except there was a important addition ( p & lt ; 0.05 ) of twenty-four hours 56 I. aquatica shoot fresh biomass in which intercropping with vaccination of GV Fungi. Furthermore, this consequence indicated that intercorpping did non impact the growing of I. aquatica.

Comparing monoculture and interculture, there were important lessening ( p & lt ; 0.05 ) of shoot Cd content in twenty-four hours 28 I. aquatica but no important different in twenty-four hours 56 I. aquatica ( Fig. 8 ) . On the other manus, there were important lessening ( p & lt ; 0.05 ) of root Cd content in both twenty-four hours 28 & A ; 56 I. aquatica ( Fig. 8 ) . This indicated that intercropping is utile for cut down Cd consumption by I. aquatica. On the other manus, comparing interculture and interculture with the vaccination of AMF, there was no important difference in twenty-four hours 28 I. aquatica shoot Cd content. However, in twenty-four hours 56 I. aquatica, there was important decrease ( P & lt ; 0.05 ) of shoot Cd content. Furthermore, with GC fungi vaccination, there were important decrease ( P & lt ; 0.05 ) of root Cd content in both twenty-four hours 28 and 56 I. aquatica ( Fig. 8 ) . These showed that AMF is utile to cut down the Cd consumption by I. aquatica.

In both twenty-four hours 28 and 56 I. aquatica, there were no obvious difference of shoot P content in all interventions ( Fig. 9 ) . Comparing monoculture and interculture, there were no important difference of root P content in both Day 28 and 56 I. aquatica ( Fig. 9 ) . This indicated that intercropping did non impact P consumption by I. aquatica. Comparing interculture and interculture with GC Fungi, there were important addition ( p & lt ; 0.05 ) of root P content in both twenty-four hours 28 and 56 I. aquatica. This indicated that intercroppping with GC Fungis vaccination could heighten the P consumption by I. aquatica. On the other manus, with GV fungi vaccination, there was important lessening ( p & lt ; 0.05 ) of root P content in twenty-four hours 28 I. aquatica and there was no important difference of root P content in twenty-four hours 56 I. aquatica.

( B )

Fig. 7- Shoot and root fresh biomass ( g ) of ( A ) twenty-four hours 28 and ( B ) twenty-four hours 56 Ipomoea aquatica with different interventions. All the informations are agencies of 5 reproductions, and the bars represent standard divergence. In different intervention, means with different letters are significantly different ( p & lt ; 0.05 ) . ( Mono: monoculture of Ipomoea aquatica ; Inter: interculture of Sedum alfredii and Ipomoea aquatica ; Inter+GC: interculture of Sedum alfredii and Ipomoea aquatica with vaccination of GC Fungi ; Inter+GV: interculture of Sedum alfredii and Ipomoea aquatica with vaccination of GV fungi. )

( B )

Fig. 8- Shoot and root Cd content ( mg kg-1 fresh biomass ) of ( A ) twenty-four hours 28 and ( B ) twenty-four hours 56 Ipomoea aquatica with different interventions. All the informations are agencies of 5 reproductions, and the bars represent standard divergence. In different intervention, means with different letters are significantly different ( p & lt ; 0.05 ) . ( Mono: monoculture of Ipomoea aquatica ; Inter: interculture of Sedum alfredii and Ipomoea aquatica ; Inter+GC: interculture of Sedum alfredii and Ipomoea aquatica with vaccination of GC Fungi ; Inter+GV: interculture of Sedum alfredii and Ipomoea aquatica with vaccination of GV fungi. )

( B )

Fig. 9- Shoot and root P content ( g kg-1 dry biomass ) of ( A ) twenty-four hours 28 and ( B ) twenty-four hours 56 Ipomoea aquatica with different interventions. All the informations are agencies of 5 reproductions, and the bars represent standard divergence. In different intervention, means with different letters are significantly different ( p & lt ; 0.05 ) . ( Mono: monoculture of Ipomoea aquatica ; Inter: interculture of Sedum alfredii and Ipomoea aquatica ; Inter+GC: interculture of Sedum alfredii and Ipomoea aquatica with vaccination of GC Fungi ; Inter+GV: interculture of Sedum alfredii and Ipomoea aquatica with vaccination of GV fungi. )

Discussion

The purpose of this survey was to analyze the consequence of AM fungi on Cd consumption by Sedum alfredii and the consequence of AMF and Sedum alfredii on Cd consumption by Ipomoea aquatica from Cd-contaminated veggie dirts, so as to cut down Cd consumption by I. aquatica. It is known that when there are inordinate concentrations of heavy metals in dirts, it is non merely toxic to workss, but besides bacteriums and Fungis ( Vivas et al. , 2003 ) . Furthermore, Cadmium is extremely toxic to works. Therefore, in this survey, intercropping with the add-on of AMF was used in order to heighten S. alfredii uptake more Cd, so as to cut down dirt available Cadmium and in bend cut down Cd consumption by I. aquatica.

4.1 Effectss of arbuscular mycorrhizal Fungi ( AMF ) on colonisation rate, works biomass, Cd content and P content of twenty-four hours 56 S. alfredii.

Although all S. alfredii were colonized by AMF ( Table 1 ) , there were important difference ( p & lt ; 0.05 ) between interventions. With vaccination of AMF, there was important increased ( P & lt ; 0.05 ) of mycorrhizal colonisation in of twenty-four hours 56 S. alfredii. This consequence is in understanding with a few studies that AMF has ability to colonise hyperaccumulator workss and accordingly increase workss biomass ( Liu et al.,2004 ) . Furthermore, the consequence shows that vaccination of GC Fungis increased dirt pH better than that of GV Fungi. This increased pH may account for the important increased ( P & lt ; 0.05 ) of twenty-four hours 56 S. alfredii biomass ( Fig. 2 ) . As the dirt is less acidic, which is much more suited for workss growing. Therefore, dry biomass of twenty-four hours 56 S. alfredii in interculture with vaccination of GC Fungi was larger than that of interculture. This addition of dry biomass of twenty-four hours 56 S. alfredii together with the important addition ( p & lt ; 0.05 ) of Cd content in it ( Fig. 3A ) , and therefore, increased Cd consumption. Furthermore, cherished study found that some mycorrhizas may heighten the ability of workss to scavenge for limited and immobile foods, particularly P ( Smith et al. , 2003 ) , so the works biomass incrased. This besides history for that, with vaccination of GC Fungi, there was important increased ( P & lt ; 0.05 ) of twenty-four hours 56 S. alfredii dry biomass ( Fig. 2 ) . However, this reult is consistent with Shen, et Al. ( 2006 ) reported that the AMF may ease works metal tolerance in a few ways. For illustration, the mycorrhiza increased works biomass, so as to thin the metals content in the works tissues, and indirectly by heightening works P nutrition with a possible farther part to heighten works biomass.

Although there were no obvious difference of P content among all interventions ( Fig. 3B ) , there was important increased ( P & lt ; 0.05 ) of twenty-four hours 56 S. alfredii dry biomass in intercropping with GC Fungis ( Fig. 2 ) , that means S. alfredii P consumption was increased. This consequence can be accounted by Smith and Read ( 1997 ) , when AM hyphae absorb P, so translocate it quickly and present P to the root, which is believed as the chief footing for AMF positive effects on P consumption and works growing. On the other manus, some research workers found that AMF can supply the regulating path for works P supply, even when overall works growing or P uptake remains unchanged ( Smith, Smith, and Jakobsen, 2003 ) . This can be accounted for intercropping with GV Fungis, although there were no signifcant differnce for dry biomass and P content of twenty-four hours 56 S. alfredii.

With vaccination of AMF, there were important increased ( P & lt ; 0.05 ) of Cd content in twenty-four hours 56 S. alfredii ( Fig. 3A ) .This consequence is consistent with Yang, et Al. ( 2004 ) reported that S. alfredii has an singular ability to absorb Cd and concentrate it in the aboveground tissues, peculiarly in the foliages. Furthermore, Yang, et Al. ( 2004 ) besides proved that, shoot growing of S. alfredii can be enhanced somewhat by Cd supply at suited levels.This proves that S. alfredii has an extraordinary ability to hyperaccumulate Cd in its shoots, that means it is a suited works stuff for Cd phytoextraction in Cd-contaminated dirts. However, the mechanisms of Cd uptake, conveyance and accretion in hyperaccumulator workss are non to the full known yet. It is suggested by Welch and Norvell ( 1999 ) that, it is believed that non-accumulator workss uptake Cd by the same bearer as for other bivalent cations, for illustration, Zn2+ , Fe2+ , or Cu2+ , or via cation, Ca2+ and Mg2+channels. The mechanisms behind the tolerance of S. alfredii to Cd needed farther probe.

To sum up, it is no uncertainty that there was an sweetening of S. alfredii Cd consumption by AMF. S. alfredii uptake more Cadmium and cut down dirt available Cd. As a consequence, intercropping is utile to cut down Cd consumption by I. aquatica.

4.2 Effectss of S. alfredii and AMF on dirt pH, EC, entire Cd content, bioavailable Cd content and P content and acerb phosphatase activity.

Although in all interventions, dirt pH & lt ; 5.5, that means they are acidic ( Fig. 4A ) . However, with intercropping, there was important addition ( p & lt ; 0.05 ) of dirt pH. As reported by Shen, et Al. ( 2006 ) , more acidic dirt conditions may increase the badness of Cd toxicity. That means intercroping is utile for addition dirt pH so as to cut down Cd toxicity to works. On the other manus, there were no important decrease of dirt entire Cd and dirt available Cd ( Fig. 5A and 5B ) among different interventions, because of the short clip period of experiment. However, it is proved by Yang, et Al. ( 2004 ) that Sedum alfredii is a powerful Cd hyperaccumulator, so it is utile for phytoremediation of Cd-contaminated dirts and hence could cut down dirt available Cd. In add-on, intercorpping caused decrease of dirt bioavailable P and important lessening ( p & lt ; 0.05 ) of dirt acerb phosphatase activity ( Fig. 6A and 6B ) . This is because both workss ( S. alfredii and I. aquatica ) absorbed alimentary from dirt at the same clip, in bend caused decrease of dirt bioavailable P. Furthermore, Moreno et Al. ( 2003 ) reported that as dirt acid phosphatase was sensitive to heavy metals and could be used as toxicity trial to set up the impact of heavy metals on the operation of the dirt. That means with intercropping, the map of dirt is weakened.

Harmonizing to the consequence, there were no obvious difference of EC among interventions ( Fig. 4B ) . EC could be used to mensurate the dissolved salt or ion concentrartion in the dirt, in which for harvest soaking up. It is known that if EC is excessively high, which is non good for harvest growing. That means in different interventions, the dirts status are similar, which did non impact the experiment consequences reading.

With AMF vaccination, dirt pH were increased significantly ( p & lt ; 0.05 ) . Furthermore, with vaccination of GC Fungi, it showed a higher ability to do obvious addition ( p & lt ; 0.05 ) of dirt pH ( Fig. 4A ) . It is reported that AMF increased dirt pH and doing metal less available for works consumption ( Shen, et al. , 2006. ) . However, harmonizing to my consequence, AMF increased dirt pH and doing metal more available for hyperaccumulator consumption. On the other manus, although there were no important difference of dirt entire Cd content among interventions ( Fig 5A ) , there were important lessening ( p & lt ; 0.05 ) of dirt available Cd content ( Fig. 5B ) in interculture with AMF vaccination. This showed that less Cd is available in dirt, due to the sweetening of Cd consumption by hyperaccumulator and that means I. aquatica could uptake less Cadmium from dirt. Furthermore, with vaccination of AMF, there were important lessening ( p & lt ; 0.05 ) of dirt bioavailable P ( Fig. 6A ) . Because AMF enhance S. alfredii uptake more P, when I. aquatica uptake P at the same clip, dirt available P decreased. In add-on, with vaccination of AMF, there were important addition ( p & lt ; 0.05 ) of dirt acerb phosphatase activity ( Fig. 6B ) . This consequence was consistent with Vivas et Al. ( 2005 ) that AM fungi can increase Cd-contaminated dirt phosphatase activities. Besides, in the P nutrition of workss, dirt phosphatase may play an of import function because it mediates the release of inorganic P from organically bound P ( Wang, et Al. 2007 ) . Wang, et Al. ( 2007 ) besides suggested that dirt enzymes are utile to bespeak the AMF possible good effects on dirt quality. When there was important addition ( p & lt ; 0.05 ) of dirt acerb phosphatase activity, that means more P is available in dirts for workss direct absoption. Harmonizing to a few yesteryear surveies, dirt enzymatic activities could be used to bespeak dirt birthrate ( Stefanic et al. , 1984 ) , soil productiveness ( Busto and Perez-Mateos, 1997 ) and dirt quality ( Dick, 1994 ) . The increasesd phosphatase activities by AMF vaccination indicate that AMF play an of import function in Cd-contaminated soils betterment. Varma ( 1998 ) suggested that the mechanisms on the dirt enzymatic activities sweetening may affect the function of AM fungi, as AM propagules themselves to synthesise dirt enzymes. It is reported that AM fungous hyphae can bring forth some hydrolytic enzymes. Therefore, dirt enzymatic activities is enhanced.

4.3 Effectss of S. alfredii and AMF on fresh biomass, Cd and P content of twenty-four hours 28 and 56 I. aquatica.

When comparing monoculture and interculture, there were no important decrease of both twenty-four hours 28 and 56 I. aquatica fresh biomass and P content ( Fig. 7 and 9 ) . These indicated that intercorpping did non impact the growing of I. aquatic. Furthermore, there were important lessening ( p & lt ; 0.05 ) of shoot Cd content in twenty-four hours 28 I. aquatica but no obvious difference shown in twenty-four hours 56 I. aquatica ( Fig. 8A and 8B ) . On the other manus, there were important lessening ( p & lt ; 0.05 ) of root Cd content in both twenty-four hours 28 and 56 I. aquatica ( Fig. 8A and 8B ) . This is because with intercropping, I. aquatica could uptake less Cd as hyperaccumulator uptake more Cadmium from dirt. This indicated that intercropping is utile for decrease of Cd consumption by I. aquatica. These consequences implied that intercropping is applicable, so that husbandmans could phytoremediate the contaminated dirts with harvests production at the same clip. Onsite field surveies are needed to further look into its feasibleness in farming area.

With GC fungi vaccination, there were no important addition of twenty-four hours 28 and 56 I. aquatica fresh biomass ( Fig. 7A and 7B ) , but there were important decrease ( P & lt ; 0.05 ) of root Cd content in both twenty-four hours 28 and 56 I. aquatic and of shoot Cd in twenty-four hours 56 I. aquatic ( Fig. 8A and 8B ) . This is because as GC fungi significantly enhanced ( P & lt ; 0.05 ) dirt acerb phosphatase activity ( Fig. 6B ) , in bend increased P consumption by S. alfredii together with the important sweetening ( p & lt ; 0.05 ) of twenty-four hours 56 S. alfredii dry biomass ( Fig. 2 ) . Consequently, this significantly enhanced ( P & lt ; 0.05 ) hyperaccumulator uptake more Cd ( Fig. 3A ) , and caused a significantly lessening ( p & lt ; 0.05 ) of dirt bioavailable Cd ( Fig. 6B ) . As a consequence, twenty-four hours 56 I. aquatica could uptake less Cd. Furthermore, there were important addition ( p & lt ; 0.05 ) of root P content in both twenty-four hours 28 and 56 I. aquatic ( Fig. 9A and 9B ) . As suggested by a few similar surveies, this decreased Cd consumption and increased P consumption may be because of Cd, which may be a phosphate parallel and so it competes with P uptake because they are both taken up via the same phosphate conveyance systems ( Ullrich-Eberius et al. , 1989 ) . However, farther probe is needed. To sum up, all these consequences proved that interculture with GC fungi vaccination is utile to heighten Cd uptake by S. alfredii and cut down Cd consumption by I. aquatica.

With GV Fungi, there were no important differences of root Cd content in both dy 28 & A ; 56 I. aquatica ( Fig. 8A and 8B ) . However, in twenty-four hours 56 I. aquatica, there was important decrease ( P & lt ; 0.05 ) of shoot Cd content ( Fig. 8B ) . At the same clip, there was important addition ( p & lt ; 0.05 ) of shoot fresh biomass in twenty-four hours 56 I. aquatica ( Fig. 7B ) . Therefore, the Cd consumption by shoot of twenty-four hours 56 I. aquatica was reduced. In add-on, as GV Fungi enhanced Cd consumption by S. alfredii ( Fig. 3A ) , doing a important lessening ( p & lt ; 0.05 ) of dirt available Cd ( Fig. 5B ) , so less Cadmium from dirts could be uptake by I. aquatica. Furthermore, this may besides related to the P consumption by twenty-four hours 56 I. aquatica. There was an obvious increased ( P & lt ; 0.05 ) of fresh biomass in shoot of twenty-four hours 56 I. aquatica ( Fig. 7B ) , as its biomass increased, that means its P consumption would be increased, although there was no important difference shown in P content of 56 I. aquatica ( Fig. 9B ) . To sum up, all these consequences showed that interculture with GV fungi vaccination is utile to increase P uptake and cut down Cd consumption of I. aquatica. This may be due to the uptake competition between Cd and P, as they are both taken up via the phosphate conveyance systems ( Meharg and Hartley-Whitaker, 2002 ) .

Decision

The present survey examined the consequence of AMF on Cd and P uptake by S. alfredii and I. aquatica from cadmium-contaminated vegetable dirts. S. alfredii is utile for phytoremediation and by utilizing intercropping, the add-on of hyperaccumulator did non impact other workss growing. However, farther on site probe is needed for the feasibleness of intercropping in farming area. Furthermore, intercropping with AMF vaccination is utile to significantly heighten ( P & lt ; 0.05 ) Cd uptake by S. alfredii, accordingly cut down dirt available Cd. As a consequence, there was significantly decrease ( P & lt ; 0.05 ) of Cd consumption by I. aquatic. This improves the nutrient safety and sub-sequently reduces human Cd consumption. Although Cd content in I. aquatica is reduced, it still can non run into the State Environmental Protection Administration of China ( 1995 ) criterion of Cd content & lt ; 0.05 mg/kg. Therefore, farther probes are needed to farther decrease of Cd content in I. aquatica and in bend better nutrient safety.

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